Summary

We are all familiar with the sleepiness experienced during sickness. What is less often appreciated is that this increased need for sleep is caused by the release of signaling molecules by our own immune and nervous systems, and not by the infectious agents themselves (1). Indeed, for the spread of a virus or a bacterium, it would be much better if we were out and about when sick, instead of sleeping. On page 509 of this issue, Toda et al. (2) reveal another facet of the interplay between sleep and immunity by identifying NEMURI (NUR), an antimicrobial peptide (AMP) produced by the fruit fly Drosophila melanogaster that also has sleep-promoting properties. Because humans synthesize more than 100 different AMPs (3), this work could have implications for interactions between sleep and immunity during human disease.